A stacked fastening device

Abstract

This utility model relates to a stacked fastening device, belonging to the field of fastener technology. It includes a through-bolt; an insulating sleeve for the through-bolt to pass through; and a sealing element disposed at the opening of adjacent insulating sleeves. The sealing element includes: an annular base and a plurality of sealing flaps integrally extending from the edge of the annular base; each sealing flap is elastically deformable and its free end abuts against the circumferential wall of the through-bolt. This effectively prevents contaminants such as conductive carbon powder, oil, and moisture from the external environment from intruding into the annular gap between the inner wall of the sleeve and the through-bolt from the opening.

Description

Technical Field

[0001] This utility model belongs to the field of fastener technology, specifically relating to a stacked fastening device. Background Technology

[0002] In large rotating electrical machines, especially hydro generators and steam turbine generators, the stator core is the core magnetic circuit component. To reduce eddy current losses caused by alternating magnetic fields during operation, the stator core is typically made of laminated silicon steel sheets.

[0003] The through-bolt acts as a fastener, firmly locking all the laminations together. Since the through-bolt itself is a metal conductor, and the stator core it passes through is also a conductor, a reliable insulation structure must be installed between the through-bolt and the stator core to prevent short-circuit faults.

[0004] A common insulation method is to install insulating sleeves on the outside of the through-bolt, which isolate the through-bolt from the inner hole of the stator core.

[0005] However, the internal environment of a generator is not clean during normal operation. Due to brush wear and the lubrication system, conductive carbon dust and oil inevitably accumulate on the surfaces of the stator and rotor. This dust and oil mist circulate within the unit with the cooling airflow and can easily penetrate the physical gaps at the joints of adjacent insulating bushings, gradually forming one or more conductive paths. This causes a continuous decrease in the insulation resistance to ground of the through-core bolts. In severe cases, the insulation can be completely broken down, resulting in multi-point grounding faults in the stator core. Utility Model Content

[0006] To address the aforementioned technical problems, this utility model provides a stacked fastening device.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A lamination fastening device is provided for use in generator stator cores, comprising:

[0009] Through-hole screw;

[0010] Insulating sleeve for the insertion of the through-hole screw;

[0011] A sealing element disposed at the opening of an adjacent insulating sleeve, the sealing element comprising:

[0012] An annular base, and a plurality of sealing flaps integrally extending from the edge of the annular base;

[0013] Each of the sealing flaps can undergo elastic deformation and its free end abuts against the circumferential wall of the through-hole screw.

[0014] Preferably, the sealing flap extends at an inclined angle from the annular base toward the axis of the through-core screw.

[0015] Preferably, the sealing flap has the following characteristics on the wall surface facing away from the opening of the insulating sleeve:

[0016] A capture structure configured to capture dust particles.

[0017] Preferably, the capturing structure is a plurality of grooves recessed within the wall surface.

[0018] Preferably, the grooves are arranged in a concentric arc shape or a grid shape.

[0019] Preferably, it includes:

[0020] An insulating varnish layer is applied to the through-core screw.

[0021] Preferably, the coating thickness of the insulating varnish layer is 50 μm to 90 μm.

[0022] Preferably, it includes:

[0023] Insulating tape is wrapped around the through-core screw.

[0024] Preferably, the insulation tape has a coating thickness of 0.5 mm to 1 mm.

[0025] Preferably, the free end of the sealing flap has a reinforcing rib structure.

[0026] Preferably, the contact surface of the reinforcing rib structure that abuts against the through-core screw has multiple grooves for storing oily sealing media.

[0027] Preferably, at the opening of the slot, the edges on both sides extend inward and contact each other to form a pair of closed and elastic sealing lips.

[0028] This utility model provides a stacked fastening device, and the beneficial effects of this utility model are reflected in:

[0029] By using a radial seal at the inlet of the insulating bushing, contaminants such as conductive carbon powder, oil, and moisture from the external environment can be effectively prevented from entering the annular gap between the inner wall of the bushing and the through-bolt. By fundamentally eliminating the intrusion path of contaminants, the cleanliness of the through-bolt insulation structure can be maintained, ensuring that its insulation performance does not deteriorate, thereby greatly improving the safety and reliability of the entire generator set operation. Attached Figure Description

[0030] Figure 1 This is a front view of the stacked fastening device proposed in this utility model;

[0031] Figure 2 This is a schematic diagram of the sealing flap in the stacked fastening device proposed in this utility model;

[0032] Figure 3 This is a top view of the sealing flap in the stacked fastening device proposed in this utility model.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Through-hole screw; 2. Insulating sleeve; 3. Base; 4. Sealing flap; 401. Reinforcing rib structure; 402. Groove; 403. Sealing lip; 5. Capture structure. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] Please see Figures 1-3 As shown, the specific embodiments provided by this utility model are as follows:

[0037] like Figure 1 As shown in the figure, this embodiment proposes a lamination fastening device, which is applied to the stator core of a large generator to fasten the stator laminations and ensure the insulation performance of its core components.

[0038] The lamination fastening device includes a long rod-shaped through-hole screw 1 and a hollow insulating sleeve 2 sleeved outside the through-hole screw 1. In the assembled state, the through-hole screw 1 passes through the interior of the insulating sleeve 2, and the insulating sleeve 2 electrically isolates the through-hole screw 1 from the external stator core hole wall.

[0039] Based on the above, a sealing element is provided at at least one end of the insulating sleeve 2. The function of this sealing element is to seal the annular gap formed between the opening of the insulating sleeve 2 and the through-bolt 1 to prevent external contaminants from entering.

[0040] like Figure 2 As shown, specifically, the end seal has an annular base 3, the shape of which is adapted to the opening of the insulating sleeve 2 for installation and positioning. Multiple independent sealing flaps 4 extend integrally from the inner edge of the annular base 3, arranged in a circumferential array. "Integral extension" means that the base 3 and all sealing flaps 4 are a seamless whole, which can be formed in one step through processes such as injection molding or compression molding.

[0041] The sealing element is preferably made of a polymer material with good elasticity, such as nitrile rubber, fluororubber, or silicone rubber. This material property ensures that each sealing flap 4 has excellent flexibility and recoverable elastic deformation capability.

[0042] During assembly, when the through-bolt 1 passes through the central hole of the annular base 3, the free ends of multiple sealing flaps 4 are compressed by the through-bolt 1, resulting in elastic deformation. In operation, these elastically deformed sealing flaps 4 continuously abut against the circumferential wall of the through-bolt with a certain preload at their free ends. Thus, the multiple elastic sealing flaps 4 together form a stable and reliable inward radial sealing surface.

[0043] Furthermore, a thin-walled, flexible connecting web is integrally connected between two adjacent sealing flaps 4. This connecting web connects all the individual sealing flaps 4 into a complete, integrated structure.

[0044] This radial seal at the source of contamination (i.e., the opening of the insulating sleeve 2) effectively prevents contaminants such as conductive carbon powder, oil, and moisture from the external environment from entering the annular gap between the inner wall of the sleeve and the through-bolt 1. By fundamentally eliminating the intrusion path of contaminants, this embodiment maintains the cleanliness of the insulation structure of the through-bolt 1, ensuring that its insulation performance does not deteriorate, thereby greatly improving the safety and reliability of the entire generator set operation.

[0045] In a preferred embodiment of the present invention, the sealing flap 4 does not extend perpendicularly to the plane of the annular base 3 to which it is connected, but extends from the annular base 3 toward the axis of the through screw 1 at a predetermined angle.

[0046] During assembly, when the through-bolt 1 needs to pass through the end seal, the end of the through-bolt 1 will first contact the inclined, open side of the sealing flap 4. This inclination angle acts as a natural guide, guiding the bolt smoothly into the seal and causing the sealing flap 4 to bend backward in a preset direction, avoiding the risk of the flap tip curling, breaking, or being damaged during installation.

[0047] In addition, in operation, this inclined structure increases the axial length of the sealing flap 4, thereby increasing the sealing and shielding area and enhancing the ability to actively block the intrusion of contaminants.

[0048] In a preferred embodiment of the present invention, a trapping structure 5 is provided on the wall surface of the sealing flap 4 facing away from the opening of the insulating sleeve 2, that is, on the side facing the outside of the insulating sleeve 2 and exposed to the potentially polluted environment.

[0049] When the stacked fastening device is working, when moving dust particles fall into the wall of the sealing flap 4, the capturing structure 5 on it can capture the dust particles by increasing the friction, thereby preventing the dust particles from moving further to the contact position between the end of the sealing flap 4 and the through screw 1.

[0050] like Figure 3 As shown, in a preferred embodiment of the present invention, the capturing structure 5 is specifically a plurality of grooves formed in the wall of the sealing flap 4.

[0051] When tiny dust particles land on a grooved wall, they are drawn into the grooves by gravity or airflow disturbance. Once inside, the bottom and sidewalls of the groove physically confine and impede the particles, making it difficult for them to escape. Simultaneously, the grooves increase the effective contact area between the particles and the lobes, thereby increasing friction and making it harder for the particles to slide or roll.

[0052] As a further optimization, the arrangement of these grooves can be designed according to specific needs. For example, they can be set as multiple concentric arc-shaped grooves, or as crisscrossing grid-like grooves.

[0053] In a preferred embodiment of this invention, a reinforcing rib structure 401 is integrally provided at the free end of the sealing flap 4, i.e., the area where it directly contacts and rubs against the circumferential wall of the through-bolt 1. The cross-sectional thickness or rigidity of the reinforcing rib structure 401 is greater than the thickness or rigidity of the main body of the sealing flap 4.

[0054] The free end of the sealing flap 4 is the part of the entire seal that bears the most concentrated friction and wear. By setting reinforcing ribs, the material allowance and structural strength of this critical part are increased, enabling it to effectively resist wear caused by friction that may occur during the insertion of the through-bolt 1 or long-term operation, thereby significantly extending the effective service life of the entire seal.

[0055] Secondly, appropriately thickened or reinforced end structures can provide a more stable and concentrated contact pressure line. This ensures that it can fit tightly against the surface of the through-bolt 1 with optimal pressure, avoiding the decrease in sealing performance that may be caused by excessively soft flaps or uneven pressure, and further improving the long-term reliability of the seal.

[0056] In a preferred embodiment of this utility model, a groove 402 is provided on the contact surface where the reinforcing rib structure 401 abuts against the through-bolt 1. The groove 402 can be pre-filled with an oily sealing medium, such as high-viscosity silicone grease, fluorinated grease or other semi-fluid sealant, before assembly.

[0057] When the equipment is running or when the through-screw 1 moves relative to the equipment, the oily medium stored in the slot 402 will continuously and in small amounts penetrate to the contact surface between the reinforcing rib and the through-screw 1, forming a stable lubricating oil film. This oil film can greatly reduce the coefficient of friction between the two, thereby reducing wear and protecting both the sealing flap 4 and the through-screw 1.

[0058] Furthermore, the oil-based sealing medium itself has the ability to fill tiny gaps. It fills all the microscopic gaps that are invisible to the naked eye between the reinforcing rib contact surface and the screw surface, forming a second sealing line of defense in addition to the elastic contact of the sealing flap 4, which can more reliably prevent the intrusion of moisture or ultrafine dust.

[0059] In a preferred embodiment of the present invention, at the opening of the slot 402, the edges on both sides extend inward and contact each other, thereby forming a pair of sealing lips 403 that are closed and elastic in their natural state.

[0060] Under static or low pressure conditions, the elastic lips remain tightly closed to each other due to their preset stress. This closed state seals the internal oily sealing medium (such as grease) within the cavity of the slot 402. When the reinforcing rib rubs against the through-bolt 1 or is subjected to greater contact pressure, the lips will undergo slight elastic separation or opening. At this time, a small amount of oily medium is squeezed out or released from inside the slot 402 onto the contact surface, serving to lubricate and supplement the seal.

[0061] In a preferred embodiment of this invention, the stacked fastening device includes an insulating varnish layer uniformly coated on the entire outer surface of the through-hole screw 1. The function of this insulating varnish layer is to completely isolate the metal substrate of the through-hole screw 1 from any external conductive medium (including moisture or intruding conductive dust) that may come into contact with it, thereby fundamentally preventing the formation of leakage or short circuit paths.

[0062] To ensure a balance between insulation performance and mechanical properties, the coating thickness of the insulating varnish layer is preferably controlled within the range of 50 μm to 90 μm.

[0063] In a preferred embodiment of this utility model, an insulating tape is also included.

[0064] Specifically, the insulating tape tightly wraps around the exterior of the through-hole screw 1. In a preferred process, the insulating tape layer is wrapped over a pre-coated and cured insulating varnish layer, thereby forming a composite insulating structure. The insulating tape is typically made of materials with high dielectric strength and excellent mechanical toughness, such as polyester film, polyimide film, or fiberglass cloth-based tape.

[0065] To achieve the desired protective effect without excessively increasing the overall diameter of the screw and affecting assembly, the thickness of the insulating tape is preferably controlled within the range of 0.5mm to 1mm.

[0066] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A lamination fastening device, applied to the stator core of a generator, characterized in that, include: Through-hole screw; Insulating sleeve for the through-hole screw; A sealing element disposed at the opening of an adjacent insulating sleeve, the sealing element comprising: An annular base, and a plurality of sealing flaps integrally extending from the edge of the annular base; Each of the sealing flaps can undergo elastic deformation and its free end abuts against the circumferential wall of the through-hole screw.

2. The stacked fastening device according to claim 1, characterized in that, The sealing flap extends at an inclined angle from the annular base toward the axis of the through-core screw.

3. The stacked fastening device according to claim 2, characterized in that, The sealing flap has the following characteristics on the wall surface facing away from the opening of the insulating sleeve: A capture structure configured to capture dust particles.

4. The stacked fastening device according to claim 3, characterized in that, The capture structure consists of multiple grooves recessed within the wall surface.

5. The stacked fastening device according to claim 4, characterized in that, The grooves are arranged in a concentric arc shape or a grid shape.

6. The stacked fastening device according to claim 1, characterized in that, The free end of the sealing flap has a reinforcing rib structure.

7. The stacked fastening device according to claim 6, characterized in that, On the contact surface where the reinforcing rib structure abuts against the through-bolt, there are multiple grooves for storing oily sealing media.

8. The stacked fastening device according to claim 7, characterized in that, At the opening of the slot, the edges on both sides extend inward and contact each other to form a pair of closed and elastic sealing lips.

9. The stacked fastening device according to claim 1, characterized in that, include: An insulating varnish layer is applied to the through-core screw; The coating thickness of the insulating varnish layer is 50 μm to 90 μm.

10. The stacked fastening device according to claim 1, characterized in that, Insulating tape is wrapped around the through-core screw; The insulation tape has a coating thickness of 0.5 mm to 1 mm.

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